Dysregulation of the immune system can result in autoimmune diseases such as atopic dermatitis and asthma. Atopic dermatitis, also referred to as eczema, is an inflammatory disease characterized by the presence of itchy and tender skin, edema, and erythema. Atopic dermatitis is common in children and infants, although the disease can occur at any age.
About 70% of atopic dermatitis patients develop asthma by “atopic march,” characterized by the progression of atopic dermatitis to asthma and allergic rhinitis. Asthma is a respiratory disorder also associated with dysregulation of the immune system. More specifically, it is a chronic respiratory disease marked by respiratory spasms and obstruction due to allergic inflammation of the bronchi, causing repetitive breathing shortness, wheezing and coughing. Asthma prevalence is estimated to be as high as 300 million individuals worldwide, and about 8% of the population of major developed countries are afflicted with asthma.
IL4Rα, F2RL1 and TRPA1 genes play a key role in the onset and progression of symptoms of atopic dermatitis and/or asthma. When exposed to foreign antigens, dendritic cells in atopic dermatitis patients activate Th2 cells, leading to the secretion of cytokines (e.g., IL-4, IL-5, IL-10, and IL-13) by the activated Th2 cells. Among the cytokines, IL-4 and IL-13 are known to play an important role in the onset of atopic dermatitis, while IL-4 and IL-13 have been reported to worsen atopic dermatitis symptoms of through the inhibition of human beta defensin-3 and filaggrin, both of which maintain the skin barrier. The receptors for IL-4 and IL-13 are heterodimers and contain IL4Rα (interleukin 4 receptor, alpha, also known as IL4Rα). Therefore, down-regulation of the IL4Rα can block out the signals of IL-4 and IL-13.
The main cause of the itching symptom experienced by atopic dermatitis patients is the overexpression of thymic stromal lymphopoietin (TSLP) in keratinocytes, which elevates the transient receptor potential (TRP) of TRP ion channels, including TRPV1 and TRPA1. Thus, the symptoms of atopic dermatitis can be treated by the inhibition of TRPA1.
Coagulation factor II (thrombin) receptor-like 1 (F2RL1, also known as protease-activated receptor 2, PAR2) is expressed by keratinocytes, activated endothelial cells, and sensory nerves in the skin and is involved in various inflammation reactions, pigmentation production, and the skin barrier function. F2RL1 plays a pivotal role in the activation of proteinases, which induce inflammation reactions and the aggravated skin conditions seen in atopic dermatitis patients.
Thus, there is a need for new and improved therapeutics targeting IL4Rα, TRPA1 and F2RL1 for the treatment or atopic dermatitis or asthma.